New At DVD Ripping. NEED EDUCATING!!!

Hey,
First of all I tried to rip a DVD by dragging the files off of a DVD. It gave me a few error messages saying that I could not copy them but I managed to find a way to rip them onto my desktop. When I viewed the video files they did not work. I could kind of hear sound and the visual was black and squares of colour would just appear. How can I get these video files (with menu's etc) onto my harddrive so I can re-burn them? Also, after I had successfully ripped the files from the DVD onto my hard drive I checked out the size of the folder and it was 7.25GB. I have 4.7 Gb DVD-Rs. Is there a way I can get this DVD ripped onto a DVD-R this size? Basically, I am looking at making complete duplicates of a couple DVDs I own (Menu's, special features, delted scenes and ALL) If you can help it would be greatly appreciated.
Cheers